To adapt to an environment with gravitational forces, physiological systems in the body have evolved which depend on gravity. One system in the body dependent upon gravity is bone structure. Bones, such as the femur, tibia, and fibula in the legs, the humerus, radius, and ulna in the arms, and vertebra in the back are maintained in response to weight bearing stresses caused by gravity. Another system in the body dependent upon gravity is body fluid distribution. Hydrostatic pressure in the vascular system, resulting from gravitational forces, maintains the distribution of fluids in the torso and limbs. The maintenance of these systems is desirable in a zero gravitational environment.
Exposure to a weightless environment, results in the deconditioning of gravity dependent physiological systems. Without gravitational forces, weight bearing stresses and hydrostatic pressure are lost. As a result, the body no longer maintain bones responsive to weight bearing stresses and body fluids migrate from the limbs to the torso. Although these responses are merely natural adaptations by the body to the weightless environment, there are concerns about the short and long term effects of these changes.
While in a weightless environment, the redistribution of body fluids has the undesirable effect of causing hemoconcentration and relative dehydration. Upon returning to a gravitational environment, the loss in bone structure often requires the body to undergo substantial reconditioning to regain the loss in bone structure. Additionally, the redistribution of body fluids often results in orthostatic hypertension. Attempts to minimize or prevent the above described deconditioning of the bone structure and the migration of bodily fluids have not been successful.
One attempted approach to minimize deconditioning of bone structure involves the performance of extensive exercises for short periods of time while in a weightless environment. These exercise periods have helped maintain some bone structure, however the amount maintained has been nominal. Additionally, these exercise periods have used up valuable time during space travel which could have been used for other purposes.
Another attempted approach to minimize the deconditioning of bone structure involves the use of dietary supplements, particularly calcium and hormone supplements. The supplements are taken to replenish calcium and other nutrients lost and to try and stimulate growth. The practice of taking these supplements has not had any effect. Apparently, without weight bearing stresses on the bone structure, the human body does not need these additional supplements and simply excretes them.
Another attempted approach to minimize the deconditioning of bone structure involves taking tetracycline. Tetracycline is known to have an effect on osteoclasts, at least for a short period of time. Osteoclasts are responsible for the loss or gain of calcium and bone mass in response to weight bearing stress. Apparently, taking tetracycline reduces or eliminates the amount of calcium and bone mass lost while in a weightless environment. Unfortunately, taking tetracycline poses a substantial health hazard to the individual using the drug, as explained below.
Allergic reactions to the use of tetracycline frequently develop, requiring treatment with immunosuppressive drugs. Although the allergic reaction can usually be treated successfully with immunosuppressive drugs, the use of these drugs increases the risk of infection from normally benign organisms. Prolonged use of a broad spectrum antibiotic, like tetracycline, can suppress many benign bacterial populations. This in turn leads to an overgrowth of organisms that are not sensitive to the drug. Mixed populations of micro-organisms keep each other in check while unbalanced microbial populations can cause disease. Infections caused by a normally benign organism are difficult to treat and are fatal in a high percentage of cases. Thus, the use of tetracycline to preserve bone structure poses two significant health risks.
Another attempted approach to minimize the deconditioning of bone structure involves the use of a set of suspenders. The suspenders deliver a physical load to the bone structure which stimulates bone maintenance. Although the suspenders deliver some physical load to the bones, the design does not deliver a sufficient physical load to significantly minimize or eliminate deconditioning of the overall bone structure.
One attempted approach to minimize the migration of body fluids to the torso from the limbs, involves the use of a suction bag which surrounds the lower extremities. The suction bag creates a pressure which draws fluids away from the torso of the individual to the lower extremities. Unfortunately, the suction bag is cumbersome to wear and thus can not be used all the time. Additionally, the negative pressure produced on the legs is painful.
Accordingly, it is an object of this invention to provide a garment for minimizing the loss in bone structure in a low gravity environment.
Another object of this invention is to provide a garment for minimizing the migration of fluids to the torso in a low gravity environment.
Another object of this invention is to provide a garment which eliminates the need for exercise periods to minimize the loss in bone structure in a low gravity environment.
Another object of this invention is to provide a garment which eliminates the need for the use of drugs to minimize the loss in bone structure in a low gravity environment. It will be used to treat osteoporosis in children.
Other objects and advantages will become apparent from the following description of the invention.